Replay officials have challenged rulings more frequently since the last time we pointed out wide disparities in replay rates during the final 2 minutes of halves.

Four referees hadn't faced a single booth-initiated challenge through Week 13. Those four referees have faced five such challenges in the last two weeks.

The challenge Walt Coleman faced in Baltimore was only the third raised against him this season in the final 2 minutes of a half, according to information I have tracked since 2003. Referees Gene Steratore, Ron Winter, Tony Corrente and Ed Hochuli have faced a combined 40 such challenges.

The NFL assigns the same replay officials to the same referees as part of an overall effort to foster continuity among crews.

If replay officials applied the same standards each game, we might expect referees to face a similar number of booth-initiated challenges over time.

That was not the case in past seasons and it isn't the case in 2008. The inconsistent numbers raise the possibility of inconsistent standards for challenges.

The chart shows booth-initiated challenges by referee. NFL games featured 33 total challenges in Week 15, a season high even without the Monday night game. Total challenges have risen each week since Week 12 (from 19 to 25 to 27 to 33).